Welding torch with a torch housing and drive for welding rod transport

ABSTRACT

In a welding torch including a torch housing ( 28 ) and, preferably, a tube bend ( 29 ) capable of being fastened thereto, wherein a drive unit ( 30 ) for feeding a welding wire ( 13 ) is arranged in the torch housing ( 29 ) and the drive unit ( 30 ) is formed by at least one pair of rollers, in particular a drive roller ( 31 ) and a pressure roller ( 32 ), as well as a drive motor, a part of the torch housing ( 28 ) is designed as a component of the drive unit ( 30 ). A rotor ( 45 ), in particular a motor shaft ( 46 ), of the drive motor ( 33 ) is fastened to the torch housing ( 28 ) via a bearing, in particular via bearings ( 43, 44 ), to stabilize and position the rotor ( 45 ). In a welding wire feed drive motor including bearings ( 43, 44 ), a rotor ( 45 ), in particular a motor shaft ( 46 ) and a rotor winding ( 49 ) or rotor magnets, and a stator pack, in particular stator winding ( 47 ) or stator magnets, at least a part of the motor shaft ( 46 ), in particular the retention zone of a drive roller ( 31 ), is electrically insulated from the housing, in particular stator housing ( 65 ) or base body ( 37 ).

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. §119 of Austrian ApplicationNo. A 160/2004 filed Feb. 4, 2004. Applicants also claim priority under35 U.S.C. §365 of PCT/AT2005/000030 filed Feb. 2, 2005. Theinternational application under PCT article 21(2) was not published inEnglish.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a welding torch including a torch housing and,preferably, a tube bend capable of being fastened thereto, wherein adrive unit for feeding a welding wire is arranged in the torch housingand the drive unit is formed by at least one pair of rollers, inparticular a drive roller and a pressure roller, as well as a drivemotor.

2. Prior Art

From the prior art, it is known that drive motors used in weldingtorches are designed as independent assemblies. In those cases, thedrive motor has its own stator house, which carries or incorporates allelements like the stator windings or stator magnets, the rotor with thestator pack, in particular rotor windings or rotor magnets, the bearingsfor the rotor, the end shield and a motor plate. That independent drivemotor assembly is fastened to the torch housing. In order to increasethe feeding power, a gearbox is fastened to the motor shaft, with adrive roller being attached to the latter to enable wire feeding with anassociated pressure roll. This involves the disadvantage of requiringadditional or more space, since that stator housing has to be realizedin a particularly stable manner for the fixation of the bearing. Anotherdisadvantage resides in that no optimum cooling of the drive motor isfeasible, since the forming rotor heat is taken up by the stator housingand no optimum heat removal takes place on account of small coolingsurfaces or respective transition resistances to the welding torch.

Another variant embodiment comprises a freely located, aircooled drivemotor. Since in that case cooling is effected via the stator housing, itis disadvantageous that only a very small cooling surface is available.

GB 911 649 A, U.S. Pat. No. 4,845,336 A, GB 1 134 664 A, GB 1 080 125 Aand GB 1 093 736 A, for instance, describe welding torch constructionsincluding drive motors which are designed as independent assembliesincluding their own stator housings.

SUMMARY OF THE INVENTION

The object of the present invention, therefore, resides in providing awelding torch or wire feed unit, respectively, of as small a structuralsize as possible and comprising an electric drive unit. Another objectof the invention consists in providing improved cooling of the driveunit so as to increase its service life.

An object of the invention also resides in providing an electric drivemotor, which ensures an electric potential separation between the driveroller and the stator housing and/or welding torch.

The object underlying the invention is achieved in that a part of thetorch housing is designed as a component of the drive unit, wherein abearing for mounting the rotor, in particular motor shaft, is fastenedto the torch housing to stabilize and position said rotor. This offersthe advantage of manufacturing tolerances between the position of themotor shaft and the welding wire feed axis being reduced due to thebearing site being located directly on the torch housing or base body,with the only manufacturing tolerance occurring when mounting thebearings within the torch housing, while the constructions known fromthe prior art involve tolerance chains due to the end shield beingmounted on the welding torch.

Another advantage resides in that a reinforced bearing can be used and,hence, adapted to the necessary loads of the welding wire feed. Anessential advantage resides in that, due to the bearing being installedin the torch housing, the distance between the bearing and the driveroller can be reduced so as to reduce the bending moment on the motorshaft and increase the service life of the motor shaft. An essentialadvantage resides, above all, in that optimum cooling is provided forthe motor parts of the drive motor, since the welding torch or torchhousing can now be utilized as cooling surfaces, thus substantiallyincreasing service life. It is essential that the heat formed by thedrive motor no longer has to be transmitted from a stator housing to acooling surface, as is known from the prior art, but that the formedheat is immediately introduced directly into the torch housing. Hence,there are no more transition surfaces on which heat can build up, whichmay lead to an overheating of the drive motor.

A configuration according to an embodiment is also advantageous in that,due to the direct integration of the drive motor in the torch housing,the stator housing usually provided at the drive motor can be omittedsuch that less space for the drive motor is required in the weldingtorch so as to reduce the structural size and weight of the weldingtorch. Consequently, also the accessibility in robotic applications issubstantially enhanced by the compact, small design and low weight. Aparticular advantage also resides in that the cross section for thetransmission of force is increased, whereas in the prior art the crosssection available for the transmission of force between the torchretainer and the tube bend is reduced due to the free arrangement of themotor, which causes a reduction of the strength of the welding torch.

The configuration according to another embodiment is advantageous, sincethe torch housing can thereby be composed of parts made of differentmaterials and having different material thicknesses so as to achieveconsiderable weight savings. The individual torch housing parts can bemade of different materials by different manufacturing processes suchas, for instance, injection moldings or sheet metals, etc., so as toenable the optimum adaptation of said parts to the respectiveapplication such as, for instance, drive motor cooling, welding torchrigidity, etc.

Moreover, the configuration according to another embodiment isadvantageous, since it allows, for instance, the production of the basebody as a casting part and, hence, a saving of weight and an increase instrength.

By the configuration according to other embodiments, it is provided inan advantageous manner that the stator pack is fixedly connected withthe torch housing such that vibrations will not have any effect on thefixation of the drive motor, whereas, according to the prior art, thefixation of the motor to the burner housing may be loosened byvibrations. It is, furthermore, advantageous that a high strength isprovided due to the enlarged cross section of the torch housing ascompared to a stator housing used in the prior art.

Yet, a configuration according to other embodiments is advantageous too,since no additional intermediate pieces for the bearings are, therefore,required. Another advantage resides in that, due to the elevatedstrength and stiffness of the torch housing as compared to aconventional stator house, a reinforced bearing can be used such thatthe service life will be substantially enhanced.

Also a configuration according to another embodiment is of advantage,providing simple mounting and a high strength.

A configuration according to another embodiment is advantageous too,since it enables the use of a rotor known from the prior art, which willreduce costs.

Also advantageous is a configuration according to another embodiment,since it offers an excellent protection of the motor parts. At the sametime, the use of an insulation plate allows the latter to be employed asa seal of the motor parts, providing simple and optimum sealing over alarge area. It is, furthermore, advantageous that a contact between thewelding wire and the torch housing will be prevented.

A configuration according to another embodiment is advantageous, sincethereby a low mass moment of inertia as well as a rapid responsebehavior of the drive unit during welding wire feeding will be achieved.

The configuration according to another embodiment advantageously ensuresthat a change in the transmission of force or rotational speed isreadily enabled by the use of a gear.

However, a configuration according to another embodiment is alsoadvantageous, since it allows for a further reduction in weight and, atthe same time, an enlargement of the inner volume of the welding torch.

A configuration according to another embodiment advantageously ensuresthat there will be no transition resistances for the heat removal of thedrive motor such that optimum cooling of the drive motor will beachieved.

Also advantageous is the configuration according to another embodiment,in which cooling of the drive motor does not exclusively occur by theambient air, but heat is additionally carried off by the aid of acoolant. Due to the integration of cooling channels directly in thehousing, no additional cooling ducts are required. If, however, coolingducts are used, a simpler torch housing construction and, hence, reducedcosts will be feasible. With a combination of cooling channels andcooling ducts, optimum cooling of the motor parts will be provided so asto enable the use of high-performance drive motors in the torch housing.

By the configuration according another embodiment, an enlargement of thesurface of the torch housing and, hence, an even better cooling will beachieved.

The configuration according to another embodiment is also advantageous,since, in the event of a manual welding torch, the grip part is used tointegrate the drive motor, so that a very small manual welding torchoffering excellent handling properties will be realized.

The configuration according to another embodiment is advantageous too,since it allows the assembly to be used with planetary gears or othertypes of gears. In addition, a further reduction of the structuraldimensions will be achieved.

The configuration according to another embodiment is also advantageous,since the sensor signals are thereby transmitted to the controlelectronics via short lines, thus reducing the susceptibility tofailures. In this respect, it is further possible to establish a simplecommunication with external control devices, for instance, via a serialbus.

An advantage of the configuration according to another embodimentresides in that with an external control device the control electronicswithin the welding torch can be reduced or omitted and the costs of thewelding torch can, hence, be reduced.

By the configuration according to another embodiment, it isadvantageously achieved that a control procedure such as, for instance,the start of the welding process or the threading-in of the welding wirecan be triggered directly from the welding torch, thus providinguser-friendliness.

Yet, also a configuration according to another embodiment is ofadvantage, since it allows for the combination of different materials soas to provide optimum handling and a very low weight of the weldingtorch. As a result, costs will be reduced too.

The configuration according to another embodiment in an advantageousmanner enables assembly expenses for the welding torch to be kept as lowas possible, since the use of a mounting plate will facilitate theassembly of the inner mechanism of the welding torch and enable thepreassembled mounting plate including the components or parts mountedthereon to be subsequently merely installed into the torch housing. Itis thereby feasible in an advantageous manner to use always the sametorch housing and assemble different embodiments adapted to therespective objectives on the mounting plate(s).

The configuration according to other embodiments is also advantageous,since as a function of the application of the welding torch, therespectively optimum drive motor can each be integrated in the same.

The configuration according to other embodiments offers the advantagethat the insulation will prevent a short-circuit and, hence, a resultingwelding current flow over the housing of the welding torch to ensureuser safety. Moreover, it is achieved that the motor parts will beinsulated and, hence, protected to increase operational safety.

However, the configuration according to another embodiment is also ofadvantage, since it enables the power transmission from the weldingcurrent supply of the welding apparatus to the connection site for thetube bend, i.e. the power supply for the contact tube, to take place viathe torch housing or parts of the torch housing, so that the respectivepower lines within the torch housing can be omitted. It also provideseasy cooling of the live parts.

The configuration according to another embodiment in an advantageousmanner will prevent a user from touching any of the live parts and,hence, risk of an electric shock or a short-circuit when contacting theworkpiece.

With a configuration according to another embodiment, it isadvantageously ensured that in the automatic use of the welding torch,e.g. on a robot, no current flow will take place between the retainerbody and the welding torch, and a failure safety on account of a weldingwire flow through the system will be provided.

The configuration according to another embodiment is also advantageous,because it offers the optimum adaptability to the respective field ofapplication of the welding torch. It is, thus, possible to produce abasic welding torch and modify the drive motor using additional modulesas a function of its application, in order to enable an adaptation ofthe power or output of the drive motor and/or the control quality and/ordynamic response behavior of the drive motor without having to exchangethe whole welding torch.

The configuration according to another embodiment is advantageous too,since it enables an actual value detection of the state or motormovement of the drive motor directly in the welding torch and, hence,appropriate controlling at a deviation from the set value. As a result,an excellent welding quality will be achieved.

Yet, also the configuration according to another embodiment isadvantageous, since it allows for the implementation of an automaticrecognition of the parameters of the drive motor so as to enable theindependent adaptation of the control and, in particular, controllingparameters by the welding system.

Also advantageous is the configuration according to another embodiment,which allows for the use of a welding torch having several drive motorsso as to obtain a higher wire feeding power or enable the use of smallerdrive motors.

The configuration according to another embodiment is advantageous too,because is provides a simple structure and a reduced tolerance chain.

The configuration according to another embodiment is also advantageous,because it ensures very simple mounting of the drive unit by the simpleinsertion into one housing half and the subsequent fixation by means ofthe other housing half.

The object of the invention will also be achieved by the configurationaccording to another embodiment. It is thereby reached in anadvantageous manner that such a construction of a drive motor integratedin a component can be used in applications other than a welding torch,i.e., such a setup is not only beneficial for welding torches, but alsoother welding wire feed systems such as, for instance, cold-wire weldingwire feeders for WIG or plasma processes or a welding wire feed arrangedoutside the welding torch can be constructed in this manner.

The invention also relates to a drive motor for feeding a welding wire,including bearings, a rotor, in particular a motor shaft and a rotorwinding or rotor magnets, and a stator pack, in particular a statorwinding or stator magnets.

In this respect, the object of the invention is achieved in that atleast a part of the motor shaft, in particular the retention zone of thedrive roller, is electrically insulated from the housing. This offersthe advantage that an electric potential on a partial region of themotor shaft is separated from the stator housing or base body and,hence, no current can flow through structural components or interfacesof the welding torch. An essential advantage resides in that noseparation of the heat flow from the heat source and, in particular,stator winding takes place to the cooling body and, in particular, torchhousing. Another advantage resides in that, for use in weldingtechnology, the driving roller can thus be mounted directly to the motorshaft without any insulation having to be provided in addition, so as toreduce manufacturing expenses and, hence, costs. A further advantageconsists in that it is thereby feasible to reduce the manufacturingtolerance chain so as to obtain an enhanced welding wire feed for use inwelding technology. Also with use in welding technology, a betterconnection of the drive roller to the motor shaft will be achieved withthe drive roller being directly mounted to the motor shaft by asteel-steel connection.

Further advantageous configurations are contained in other embodiments.The advantages resulting therefrom can be taken from the description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail by way of theaccompanying drawings, which show exemplary embodiments of the weldingtorch. Therein:

FIG. 1 is a schematic illustration of a welding installation orapparatus;

FIG. 2 is an elevational view of a welding torch in the assembled state;

FIG. 3 is an elevational view with the cover part removed;

FIG. 4 is an explosive view of the welding torch and the integral drivemotor in a simplified, schematic illustration;

FIG. 5 is a section through the welding torch in a side view andsimplified, schematic illustration;

FIG. 6 shows another embodiment of the welding torch in a simplified,schematic illustration;

FIG. 7 shows another embodiment of the welding torch in a simplified,schematic illustration;

FIG. 8 shows another setup of the welding torch and integrated drivemotor in a simplified, schematic illustration;

FIG. 9 shows an option of expansion of the welding torch in asimplified, schematic illustration;

FIGS. 10 and 11 in simplified, schematic illustrations show options ofadaptation of the output or response behavior of a drive motor, with thedrive motor being integrated in the welding torch;

FIG. 12 depicts another exemplary embodiment of a welding torch assemblywith an integrated drive motor;

FIG. 13 depicts an embodiment of a manual welding torch; and

FIGS. 14 to 19 show different configurations of an exemplary embodimentof a drive motor as an independent structural unit in simplified,schematic illustrations.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 depicts a welding apparatus 1, or welding system, for variousprocesses or methods such as, e.g., MIG/MAG welding or WIG/TIG welding,or electrode welding methods, doublewire/tandem welding methods, plasmaor soldering methods etc.

The welding apparatus 1 comprises a power source 2 including a powerelement 3, a control device 4, and a switch member 5 associated with thepower element 3 and control device 4, respectively. The switch member 5and the control device 4 are connected to a control valve 6 arranged ina feed line 7 for a gas 8, in particular a protective gas such as, forinstance, carbon dioxide, helium or argon and the like, between a gasreservoir 9 and a welding torch 10 or torch.

In addition, a wire feeder 11, which is usually employed in MIG/MAGwelding, can be controlled by the control device 4, whereby a fillermaterial or welding wire 13 is fed from a feed drum 14 or wire coil intothe region of the welding torch 10 via a feed line 12. It is, of course,possible to integrate the wire feeder 11 in the welding apparatus 1 and,in particular, its basic housing, as is known from the prior art, ratherthan designing the same as an accessory device as illustrated in FIG. 1.It is also feasible for the wire feeder 11 to supply the welding wire13, or filler metal, to the process site outside the welding torch 10,to which end a non-consumable electrode is preferably arranged withinthe welding torch 10, as is usually the case with WIG/TIG welding.

The power required to build up an electric arc 15, in particular anoperative electric arc, between the electrode or welding wire 13,respectively, and a workpiece 16 is supplied from the power element 3 ofthe power source 2 to the welding torch 10, in particular electrode, viaa welding line 17, wherein the workpiece 16 to be welded, which ispreferably formed by several parts, via a further welding line 18 islikewise connected with the welding apparatus 1 and, in particular,power source 2 so as to enable a power circuit for a process to build upover the electric arc 15, or a plasma jet formed.

To provide cooling of the welding torch 10, the welding torch 10 can beconnected to a fluid reservoir, in particular a water reservoir 21, by acooling circuit 19, for instance, via an interposed flow control 20, soas to cause the cooling circuit 19, in particular a fluid pump used forthe fluid contained in the water reservoir 21, to be started as thewelding torch 10 is put into operation, in order to effect cooling ofthe welding torch 10 by feeding a cooling medium.

The welding apparatus 1 further comprises an input and/or output device22, via which the most different welding parameters, operating modes orwelding programs of the welding apparatus 1 can be set and called,respectively. In doing so, the welding parameters, operating modes orwelding programs set via the input and/or output device 22 aretransmitted to the control device 4, which subsequently controls theindividual components of the welding system or welding apparatus 1and/or predetermines the respective set values for controlling.

In the exemplary embodiment illustrated, the welding torch 10 is,furthermore, connected with the welding apparatus 1 or welding systemvia a hose pack 23. The hose pack 23 houses the individual lines fromthe welding apparatus 1 to the welding torch 10. The hose pack 23 isconnected with the welding torch 10 via a coupling mechanism 24, whereasthe individual lines arranged in the hose pack 23 are connected with theindividual contacts of the welding apparatus 1 via connection sockets orplug-in connections. In order to ensure an appropriate strain relief ofthe hose pack 23, the hose pack 23 is connected with a housing 26, inparticular the basic housing of the welding apparatus 1, via a strainrelief means 25. It is, of course, also possible to use the couplingmechanism 24 for connection to the welding apparatus 1.

It should basically be noted that not all of the previously mentionedcomponents have to be used or employed for the various welding methodsor welding apparatus 1 such as, e.g., WIG devices or MIG/MAG apparatusor plasma devices. Thus, it is, for instance, possible to devise thewelding torch 10 as an aircooled welding torch 10.

FIGS. 2 to 5 schematically illustrate the setup of a welding torch 10according to the invention, which is used for robotic applications, andwherein the welding torch 10 can be fastened to a manipulator 27 of arobot (not illustrated).

The welding torch 10 comprises at least a torch housing 28 and,preferably, a tube bend 29 capable of being fastened to the former,wherein a drive unit 30 for feeding the welding wire 13 is arrangedwithin the torch housing 28. The drive unit 30 is formed by at least onepair of rollers, in particular a drive roller 31 and a pressure roller32, as well as a drive motor 33. In order to provide optimum weldingwire feeding, it is necessary to build up a defined pressure force onthe welding wire 13 via the rollers and, in particular, the pressureroller 32. This is, for instance, feasible in that the pressure roller32 is movably mounted via a pivot lever 34, said pivot lever 34 beingfixed via a tension lever 35. The tension force of the tension lever 35is varied in a simple manner using a setting device 36, particularlyscrew, wherein the tension lever 35 presses the pivot lever 34 by thepressure roller 32 in the direction of the drive roller 31. It isthereby reached that the pressure roller 32 is pressed against the driveroller 31 via the rotationally mounted pivot lever 34 so as to build upan appropriate force on the welding wire 13 via the drive roller 31 andthe pressure roller 32 as the welding wire is passed therethrough.

In a preferred manner, the torch housing 28 is comprised of severalparts such as, for instance, a base body 37, a cover part 38, a controlelectronics part 39, a torch retainer 40 etc. Furthermore, the weldingtorch 10 carries coupling mechanisms 41 to which the tube bend 29 andthe hose pack 23 can be coupled. A detailed illustration of the internalsetup for the laying of lines 42 and/or tubes for feeding media, inparticular cooling ducts and gas feed lines as well as a welding powerfeed line etc., between the coupling devices 41 is obviated for the sakeof clarity, so that the respective fastening sites and/or guides are notillustrated.

With the welding torch 10 according to the invention, it is providedthat a part of the torch housing 28 is designed as a component of thedrive unit 33, wherein bearings 43, 44 for mounting the rotor 45, inparticular a motor shaft or the motor shaft 46, are fastened to thetorch housing 28 to stabilize and position the rotor 45. A prior artdrive motor 33 is usually constructed as a separate structural unit,i.e. with its own stator housing to which the bearings 43, 44 formounting the rotor 45 are fastened, the prior art drive motor 33 beinginstalled in, or fastened to, the torch housing 28 only as an overallunit.

The integration according to the invention, of the drive unit 30 and, inparticular, drive motor 33 in the torch housing 28 and, in particularbase body 37, enables the structural size and weight of the weldingtorch 10 to be substantially reduced, using the torch housing 28 for thestability of the drive motor 33, which means that the bending momentsand bearing forces occurring during the operation of the drive motor 33are taken up by the torch housing 28, whereas, in accordance with theprior art, these forces are transmitted to the stator housing, via whichthe drive motor 33 is fastened to the torch housing 28 according to theprior art, so as to require a relatively stable stator housing. With theconstruction according to the invention the torch housing 28, or a partof the torch housing 28, forms the stator housing, wherein, as afunction of the design of the drive unit 30, a winding pack,particularly the stator winding 47 of the drive motor 33, is directlyinstalled, particularly pressed, glued or shrunk, in the torch housing28 and, in particularly, base body 37. In this respect, it is alsopossible to press or install magnets, in particular the stator magnets,directly into the torch housing 28, particularly base body 37, if arespective drive motor of such a design is used. In this case, the basebody 37 is preferably made of one part. In the base body 37, anappropriate free space or opening 48 is provided for the integration ofthe stator pack, into which the stator winding 47 or the stator magnetsare pressed in or installed.

Furthermore, at least one bearing 43, 44, yet preferably two bearings43, 44, for the rotor 45 of the drive motor 33 are directly connectedwith the torch housing 28, particularly base body 37, wherein the rotor45 is designed as a motor shaft 46 including a rotor pack, in particularrotor winding 49 or rotor magnet, so that the motor shaft 46 isrotationally mounted on the base body 37 via bearings 43, 44 and therotor pack is arranged within the stator pack, in particular statorwinding 47 or stator magnets. An intermediate piece 50 or bearing shieldis preferably used to fasten the bearing 43, 44, said intermediate piece50 with the integrated bearing 43 being fastened to the torch housing 28and, in particular, base body 37. In this respect, it is possible toprovide an insulation plate 51 on the intermediate piece 50 as anelectrical insulation. It is, of course, also possible that theintermediate piece 50 is made of an electrically non-conductive materialand the bearing 43, 44 is embedded in the intermediate piece 50 so as toprovide an appropriate insulation plane.

In the exemplary embodiment illustrated in FIGS. 2 to 5, the opening 48for the stator pack is designed to have approximately the same diameteras the stator pack, i.e. the stator winding 47, the opening 47 extendingthroughout the entire base body 37. Mounting of the components of thedrive motor 33 is, thus, feasible on both ends. In the end region of theopening 48, the intermediate pieces 50 with the bearing 43, 44 aresubsequently mounted. To this end, the rotor 45 is inserted into theopening 48, i.e. the stator, after having mounted the stator winding 47,with the bearings 43, 44 being subsequently fastened to the motor shaft46 and the latter being fastened to the base body 37 via theintermediate piece 50 so as to ensure the stabilization and positioningof the rotor 45 in the center of the stator pack. Thus, thefunctionality of a commercially available drive motor 33 is provided,with essential advantages resulting from its integration in the housingof the welding torch 10.

In order to enable feeding of the welding wire 13, the drive roller 31subsequently is preferably directly connected with the motor shaft 46,as is schematically illustrated in FIG. 5, so as to allow for themounting of the pressure roller 32, which is fastened to the pivot lever34. The welding wire 13 can be conveyed by the drive unit 30 accordingto the direction of rotation of the drive roller 31. In the exemplaryembodiment illustrated, the welding wire 13 is supplied independently ofthe hose pack 23, via its own welding wire feed hose (not illustrated)which is coupled to the welding torch 10 by a further coupling mechanism41 and, in particular, quick-lock. The connection of the drive roller 31with the drive motor 33 can be realized in a manner that either thedrive roller 31 is directly fastened to the motor shaft 46 asillustrated in FIG. 5 or the motor shaft 46 is connected with a gear(not illustrated) with the drive roller 31 being coupled to said gear.When using a gear, the feeding power can be substantially increased. Theinsulation plate 51 and/or the intermediate piece 50 in this case can bearranged on the end face of the gear, or simply omitted.

In order to ensure optimum cooling of the drive motor 33, it is possiblethat the torch housing 28, in particular the base body 37, is designedas a cooling body, i.e., the torch housing 28 or a part of it,particularly the base body 37, is made of a heat-conductive material, inparticular aluminum, so as to enable an excellent discharge of the heatgenerated by the electric drive unit 30. To this end, it is alsopossible that the torch housing 28 or base body 37 comprises coolingchannels (not illustrated) in the region of the drive motor 33, i.e.stator pack, which means that cooling channels are directly incorporatedin the material of the base body 37. It is further possible to arrangecooling ducts 52 as schematically indicated in FIG. 4 in addition to, orinstead of, the cooling channels. In a preferred manner, the coolingchannels and/or cooling ducts 52 are line-connected with a coolingcircuit so as to enable a cooling liquid or cooling gas or air to beconveyed through the cooling channels or cooling ducts 52 and, hence,the heat to be carried off. It is, of course, also possible to couplethe cooling channels or cooling ducts 52 with the gas supply to thewelding torch 10 so as to enable the gas 8, in particular protectivegas, to be used for cooling the drive unit 30 and, at the same time,building up a protective gas atmosphere on the welding site. When usingcooling channels and/or cooling ducts, it is also possible to make thetorch housing 28 or base body 37 of a poorly heat-conductive material,for instance plastic, with sufficient heat having to be carried off bythe cooling medium through appropriately dimensioned cooling channels orcooling ducts.

If the torch housing 28, in particular the base body 37, is designed asa cooling body, good air-cooling will be essential, i.e., a very largesurface will have to be provided for aircooling. To this end, it ispossible that the torch housing 28 or base body 37 comprises coolingribs 53 on its outer side, as is schematically indicated in FIG. 4, inorder to produce an even larger surface. It is, of course, also possibleto make the housing 28 or base body 37 of a thermally well conductivematerial for air-cooling while, at the same time, using cooling channelsand/or cooling ducts 52 for liquid cooling. The welding torch 10 mayconsequently be used for very high outputs and, in particular, highwelding currents, while nevertheless keeping the structural size andweight low, since excellent cooling is provided in any event. If,however, a welding torch 10 is to be built with as little weight aspossible, the torch housing 28, or part of it, can be made of asynthetic material, since heat losses will be carried off via anappropriate cooling system.

To control the drive motor 33 in terms of speed, output and/or torque, asensor or control electronics (not illustrated) can be used in the torchhousing 28 to control the drive motor 33. In the exemplary embodimentillustrated, a separate sensor or control electronics part 39 isconnected with the base body 37. The control electronics is specificallyarranged in the detachably connected control electronics part 39 so asto provide sufficient space. It is, of course, possible to place thecontrol electronics not in a extra control electronics part 39, butintegrate it directly in the base body 37, for instance beside the drivemotor 33. The configuration and function of the control electronics willnot be described in detail, since any structure known from the prior artcan be used for this purpose, a variety of control electronics beingapplicable as a function of the type of the drive motor 33. By theseparate arrangement in a special control electronics part 39, anexchange of the control electronics is readily feasible too. It is, forinstance, possible to configure the drive motor 33 integrated in thebase body 37 as a synchro motor or direct-current motor or step motor.By using an extra control electronics part 39 which can be coupled tothe base body 37, sufficient space will be available for differentcontrol electronics so as to enable a conversion of the welding torch10, or the use of an accordingly larger control electronics part 39 inthe case of an increased amount of control electronics, without havingto exchange the whole welding torch 10 for a different controlelectronics, as is frequently necessary with welding torches 10 knownfrom the prior art. It is also possible to arrange the controlelectronics for the drive motor 33 externally, particularly within thewelding apparatus 1 or a wire feed device 11 etc., which willsubsequently be line-connected with the drive motor 33, so that thecontrol electronics part 39 can be omitted. It is, of course, alsopossible to effect the respective control directly from the controldevice 4 of the welding apparatus 1 or any other control device ofanother component, so that no extra control electronics will be requiredfor the drive motor 33 in the welding torch 10.

For a better control, an encoder 39 a may, moreover, be connected withthe rotor 45 or the drive roller 31. As encoder, any encoder known fromthe prior art, e.g. an incremental encoder, can be used. It is,furthermore, advantageous that the individual parts of the drive unit30, for the recognition of the characteristics of the drive motor 33,may comprise a memory module such as, e.g. a transponder, to enableautomatic recognition such that the respective program and/or data forthe drive unit 30 employed can be loaded or applied by the weldingapparatus 1 or by the control electronics.

In order to ensure the safety of the components of the controlelectronics and other parts of the drive motor 33 as well as thereliability of the welding torch 10, it will be advantageous if aninsulation is arranged between the drive roller 31 and the base body 37,since the transmission of welding current to the welding wire, as arule, is effected via a contact tube in the end region of the tube bend29, whereby the welding voltage potential is conducted via the weldingwire 13 to the drive roller 31 and, hence, to the drive motor 33. In theevent of a short-circuit, the resulting high welding current would causedamage to individual torch components or the entire torch, which will beprevented by the attachment of an insulation. To this end, theinsulation is preferably comprised of an insulation layer 54 made of anelectrically non-conductive material and formed between the drive roller31 and the motor shaft 46 and/or the motor shaft 46 and the rotor packand/or the motor shaft 46 and the bearings 43, 44 and/or the rotor packand the stator and/or the stator and the torch housing 28. A detailedillustration of specific insulation arrangements will be shown anddescribed in the Figures to come. It is also possible that the driveroller 31 and/or motor shaft 46 are made of an electricallynon-conductive material or parts of electrically non-conductivematerial.

In the exemplary embodiment illustrated in FIGS. 2 to 5, the insulationlayer 54 is applied on the motor shaft 46 over a partial region,particularly its end region, with the drive roller 31 being mounted inthis region of the insulation layer 54. Thus, an insulation between thedrive roller 31 and the drive motor 33, i.e. between the motor shaft 46and the drive roller 31, is provided so as to prevent welding currentfrom being transmitted onto the rotor pack and provide protection fromthe welding current also to the remaining structural elements. Theinsulation layer 54 can, for instance, be made of a plastic or ceramicmaterial. It is also possible to make the entire drive roller 31 of anelectrically non-conductive material, in which case no currenttransmission to the motor shaft 46 will occur, either. It is, of course,also possible to design the motor shaft 46 in two parts, said two partsbeing interconnected so as to be electrically insulated relative to eachother by an insulating coupling.

Furthermore, special configurations of the welding torch 10 may beenvisaged. Thus, it is, for instance, possible that the torch housing 28or a part of it, particularly the base body 37, is designed as a livepart, in particular, for the transmission of the welding current, whichmeans that the welding current fed via the hose pack 23 is conductedthrough the electrically conductive material or torch housing 28 to thetube bend 29, or a connection element for the tube bend 29. The currentcable or current transmission element provided in the torch housing 28between the two coupling mechanisms 41 can, thus, be dropped. It is,however, also necessary to externally protect from contacting thehousing part via which the welding current is conducted. This is, forinstance, feasible in that an insulation layer or an electricallynon-conductive hood (not illustrated) is applied over the torch housing28 or its live part. In a preferred manner, an insulation layer (notillustrated) is also provided between the torch retainer 40, inparticular extension part, and the torch housing 28, in particular thebase body 37, in order to prevent in any event a short-circuit via therobot and, in particular, the manipulator 27. To this end, it ispossible to make the torch retainer 40 and/or attachment part of aelectrically non-conductive material, wherein it has to be taken carethat the torch retainer 27 is made as rigid as possible for the weldingtorch 10 to remain in the same position all the time.

FIGS. 6 and 7 depict two further exemplary embodiments of the weldingtorch 10. The difference from the construction according to FIGS. 2 to 5resides in that the opening 48 provided in the base body 37 no longerextends throughout the whole base body 37, but is closed on one side,which means that in the base body 37 on one side of the opening 38 justone bearing bore or shaft passage is arranged, through which the bearing43 or 44 is directly installed into the base body 37, whereas theopposite side of the opening 38 has such a large diameter as to allowthe stator, particularly the stator winding 47 or stator magnets, to beinserted. As a result, an additional fastening means for the fixation ofthe bearing, like, for instance, the intermediate piece 50, can beobviated on the side where the bearing 43, 44 is directly installed inthe base body 37. To this end, the construction according to FIG. 6 issuch that the bearing 43 located next to the drive roller 31 is directlyembedded in the base body 37, whereas, in the construction according toFIG. 7, the bearing 44, i.e. the bearing 44 located farther remote fromthe drive roller 31, is arranged in the base body 37. In theconstruction according to FIGS. 6 and 7, the installation of theindividual parts of the drive motor 33 in this case is possible justfrom one side, yet while enhancing the stability or rigidity of thetorch housing 28 and, in particular, base body 37.

According to the exemplary embodiment depicted in FIG. 8, a mountingelement 55 to which the required parts or guides are attached is addedto the torch housing 28. The mounting element 55, for instance, carriesthe cover part 38 to protect said parts against contamination andcontacting. The welding torch 10 in this case is constructed in a mannerthat the drive motor 33 is integrated in the base body 37 and the basebody 37, on the side where the motor shaft 46 for connection with thedrive roller 31 or gear projects out of the base body 37, comprises amounting platform 56 to which the mounting element 55 is fastened. Thedesign of the mounting platform 56 is not critical. It may, forinstance, be realized by a plane surface as illustrated so as to enablea simple mounting plate, or the mounting element 55, to be mounted tothis mounting platform 56. It is, of course, also possible for themounting platform 56 to have a special contour on which an accordinglydesigned mounting element 55 will subsequently be placed.

With such a configuration of the welding torch 10, it is ensured thatany part or element such as, for instance, the coupling mechanisms 41for the tube bend 29 and the hose pack 23, the lines 42 for connectingthe two coupling mechanisms 41 as well as the bearing of the pressureroller 32 can be assembled or mounted on the mounting element 55independently of the base body 37. On the other hand, the parts for thedrive motor 33 are mounted in the base body 37. Subsequently, the twoparts, i.e. the base body 37 and the mounting element 55, merely have tobe connected with each other to obtain a functioning welding torch 10.

Very simple and quick mounting of the welding torch 10 is therebyensured in an advantageous manner. Another advantage resides in that astandardized construction of the base body 37 with the drive motor 33 isused, on which different constructions of different welding torchconfigurations can subsequently be mounted so as to no longer requiredifferent complete torch housings 28 for the great variety of weldingtorch types. Thus, considerable cost savings will be achieved, since thewelding torch construction will always be mounted on the standardizedbase body 37 with just the mounting element 55 having to be differentlyconstructed as a function of the respective welding torch type.

FIGS. 9 to 11 depict a variant embodiment in which the welding torch 10can be modularly expanded and the output of the drive motor 33 can bereadily adapted accordingly.

To this end, the drive motor 33, particularly the stator winding 47 orthe stator magnets and/or the rotor winding 49 or rotor magnets, areexpandable by additional modules 57, in particular, to adapt the outputand response behavior of the drive motor 33. This is, for instance,effected in that, as is apparent from FIG. 9, just one or severalmodules 57 are coupled to the base body 37 such that an accordinglylonger stator winding 47 and an appropriate rotor 45 can subsequently beinstalled. It is thereby achieved in an advantageous manner that alwaysthe same torch housing 28, or the same base body 37, respectively, canbe used for varying outputs of the drive motor 33, with an accordinglylarger drive motor 33 having an increased motor power being installabledue to the expansion of the base body 37 by the modules 57. The costs ofthe welding torch 10 can, thus, be kept low, using always the same torchhousing 28 rather than requiring different torch housings 28 fordifferent drive motors 33.

A special adaptation of the output or response behavior of the drivemotor 33 is apparent from FIGS. 10 and 11. In this case, the base body37 is dimensioned for an appropriate stator winding 47 with the outputor response behavior of the drive motor 33 being determined by therotor. This is effected in that, for instance, a smaller rotor pack, inparticular a smaller rotor winding 49 as illustrated in FIG. 10, is usedto provide an excellent response behavior of the drive motor 33. Thedrive motor 33 will, thus, very quickly react to a pregiven change inspeed or reversal of direction. If, however, a higher output isrequired, it will do to replace the rotor with a rotor having a largerrotor pack, in particular rotor winding 49 as is apparent from FIG. 11.

FIG. 12 illustrates a further exemplary embodiment of a construction tointegrate the drive motor 33 in the welding torch 10 and, in particular,base body 37. Here, the torch housing 28 is divided along a rotor axis,i.e., the base body 37 is now formed by two semi-shells 58, 59 in whichthe drive motor 33 is integrated. This construction provides very simplemounting, since the drive motor parts merely have to be inserted in oneof the semi-shells 58 or 59 and will subsequently be fixed or fastenedby fastening the second semi-shell 59 or 58 to the first semi-shells 58or 59, respectively.

It is, moreover, possible to realize the construction with the drivemotor 33 integrated in the torch housing 28 even with a manual weldingtorch 60, as is schematically illustrated in FIG. 13. The torch housing28 is designed as a gun welding torch with the drive motor 33 beinginstalled in the torch housing 28 in the region of the grip 61, as isschematically indicated by dot-and-dash lines. To this end, the drivemotor 33, in particular the motor shaft 46, is again arranged at anangle 62 of about 90° relative to the welding wire 13, which means thata rotor axis 63 extending in the middle of the motor shaft 46 isoriented at an angle 62 of 900 relative to a welding wire feed axis 64extending in the middle of the welding wire 13. Such an orientation ofthe drive motor 33 relative to the welding wire 13 also applies toprevious FIGS. 1 to 12. It is thereby again possible to mount the driveroller 31 directly on the motor shaft 46 and, hence, realize a directdrive for the welding wire feed.

It is, however, also possible to configure the welding torch 10, inparticular the manual welding torch 60, in a different way by orientingthe rotor axis 63 relative to the welding wire feed axis 64 no longer atan angle of 90° as in previously described FIGS. 1 to 13, but by makingthe orientation of the rotor axis 63 relative to the welding wire feedaxis 64 to extend centrically or in parallel. Such an exemplaryembodiment is, however, not illustrated, since in that case only thebase body 37 will have to be accordingly designed to integrate the drivemotor 33. With a welding torch 10 or manual welding torch 60, this may,for instance, be realized by a planetary gear for the welding wire feed,to which end the motor shaft 46 is arranged axially to the welding wire13, in particular welding wire feed axis 64, and the welding wire 13extends through the motor shaft 46, which is designed to be hollow.Naturally, it is also possible to arrange the drive motor 33 in parallelrather than in the welding wire axis, and integrate it into the basebody 37.

Basically, it should be noted that in the previously shown exemplaryembodiments of FIGS. 1 to 13 at least one or several switching elements(not illustrated) are integrated in the torch housing 28 or base body37, respectively, which switching elements serve to control the weldingprocess in a manner already known from the prior art. It is, moreover,possible to arrange several drive motors 33 in the torch housing 28 orbase body 37, which are again integrated in the torch housing 28. Inthis respect, it is also possible to integrate but one drive motor 33 inthe torch housing 28 and additionally install one or several furtherdrive motors in the torch housing 28 as in accordance with the prior artdesign including a stator housing. By the integration or use of severaldrive motors 33, it is feasible to devise a welding torch 10 with amulti-roller drive. It is also possible to use but one drive roller 31with a drive motor 33, as is known from the prior art, yet toappropriately couple further rollers with the drive roller 31, whichmeans that appropriate coupling of the individual rollers is, forinstance, realized by using toothed wheels so as to ensure a suitableforce transmission to all or some of the rollers via the one drive motor31 employed.

FIGS. 14 to 19 illustrate an independent drive motor 33 in differentstructural variants. Here, the drive motor 33 is configured as anindependent structural unit, i.e. with a stator housing 65.

The drive motor 33 contains the stator housing 65, to the end sides ofwhich a bearing shield or an intermediate piece 50 is each fastened witha respective bearing 43, 44 integrated therein. The stator pack, inparticular stator winding 47, is arranged in the interior of the statorhousing 65. The drive motor 33 further comprises a rotor 45, which isformed by a motor shaft 46 with a rotor pack, in particular rotor magnet49, fastened thereto. The rotor 45 is arranged in the center of thestator pack or stator housing 65 such that the rotor pack is arrangedwithin the stator pack. The rotor 45 is rotationally held via bearings43, 44.

According to the invention, it is provided that the drive motorcomprises a special electrical insulation, which may be arranged indifferent regions of the drive motor 33, said electrical insulationbeing formed by an insulation layer 54. It is especially provided thatat least a part of the motor shaft 46, in particular the drive rollretention zone, is electrically insulated from a housing, in particularthe stator housing 65 or the base body 37 of an external component suchas the welding torch 10. In this context, it should be mentioned thatthis construction of the drive motor 33 according to the invention withthe insulation layer 54 can also be used in the previously describedexemplary embodiments of FIGS. 1 to 13, to which end it will do toremove the stator housing 65 so as to enable the remaining parts of thedrive motor 33 to be installed in the torch housing 28 and, inparticular, base body 37. By the arrangement of the insulation layer 54it is ensured that an electric potential on a partial region of themotor shaft 46 is separated from the stator housing 65 or base body 37and, hence, no current will flow to the welding torch 10 over structuralcomponents of the drive motor 33 or any interfaces. An advantage alsoresides in that for an application in welding technology the driveroller 31 can be directly mounted to the motor shaft 46 without anadditional insulation having to be arranged so as to reducemanufacturing expenses and, hence, costs.

In the embodiment illustrated in FIG. 15, the insulation layer 54 isarranged on the outer circumference of the rotor pack, in particularrotor magnets 49. At the same time, bearings 43, 44 are likewiseinsulated relative to the stator housing 65 by an appropriate insulationlayer 54. If, for instance, an electrically conductive drive roller 31is directly fastened to the motor shaft 46, a current flow is able topropagate from the drive roller 31 via the motor shaft 46 and the rotormagnets 49, yet this current flow will subsequently be stopped onaccount of the insulation layer 54, thus preventing its spreading to thestator winding 47 and stator housing 65. The inevitable or inherentlypresent air gap in the drive motor 33 does not suffice for an insulationcomplying with the respective safety regulations.

In FIG. 16, the insulation layer is arranged between the motor shaft 46and the rotor pack, in particular rotor magnets 49, and, in addition,also the bearing sites, in particular bearings 43, 44, are insulatedsuch that no current flow can take place to the stator via the motorshaft 46.

According to the configuration shown in FIG. 17, the insulation layer 54is arranged between the stator housing 65 and the stator pack, inparticular stator winding body, to which end the bearings 43, 44 areagain electrically insulated relative to the stator housing 65.

From FIG. 18, it is apparent that the insulation layer is arranged onthe inner surface of the stator winding, in particular on the sidefacing the rotor magnets 49, and, in addition, also the bearing sites,in particular bearings 46, 47, are insulated.

It is, however, also possible according to FIG. 19, that the insulationlayer 54 is only applied or arranged over a partial region of the motorshaft 46, in particular in the end region of the drive roller 31, whichmeans that the insulation layer 54 is arranged in the region where alive part abuts or is fastened. Since, at an application in weldingtechnology, the welding wire 13 is powered with current, a current flowwill take place over the welding wire 13 to the drive roller 31. If thedrive roller 31 is directly mounted to the motor shaft 46, a respectivecurrent flow from the drive roller 31 to the motor shaft 46 may occur.By arranging the insulation layer 54 in the mounting zone of the driveroller 31, this can be readily prevented. With this solution, it is notnecessary to electrically insulate that the bearing, in particularbearings 43, 44, relative to the stator housing 65, since a current flowcan in no way act on the drive motor 31.

The insulation of the bearings 43, 44 as shown in FIGS. 14 to 19 allowsthe bearing site, in particular bearing 43 and 44, to be pressed into aninsulation sleeve. It is, however, also possible to form the bearingsite, in particular bearings 43 and 44, by an insulating hybrid bearingin which ceramic roll bodies are inserted or a bearing ring made ofelectrically nonconductive material is formed.

It is, of course, also possible to make the motor shaft 46 of anelectrically non-conductive material, in particular ceramic material,whereby the same electrically insulating effect will be achieved, yetwithout using insulation layers 54.

The invention claimed is:
 1. A welding torch comprising: a torch housingcomprising a base body, said base body comprising an outermost wall ofthe welding torch; and a drive unit arranged in said torch housing forfeeding a welding wire, said drive unit comprising: a drive roller: apressure roller; and a drive motor, said drive motor comprising: i) astator housing; ii) stator winding or stator magnets directly installedin the base body of the torch housing; iii) a rotor; and iv) bearingsprovided on or within said base body of said torch housing to stabilizeand position said rotor; wherein said base body forms said statorhousing of said drive motor, such that said stator winding or statormagnets are directly installed in said outermost wall of the weldingtorch and wherein said stator winding or stator magnets are in directcontact with said outermost wall of the welding torch.
 2. A weldingtorch according to claim 1, wherein the torch housing comprises severalparts.
 3. A welding torch according to claim 1, wherein the torchhousing further comprises a cover part, and an extension part or torchretainer.
 4. A welding torch according to claim 3, wherein the base bodyis formed by a part including a free space or opening to receive theindividual parts of the drive motor and to which further elements areattachable.
 5. A welding torch according to claim 1, wherein thebearings are directly integrated in the torch housing.
 6. A weldingtorch according to claim 1, wherein the bearings are mounted in anintermediate piece and the intermediate piece is directly fastened tothe torch housing.
 7. A welding torch according to claim 6, wherein onebearing is fixedly connected with the torch housing and a furtherbearing is detachably fastened thereto.
 8. A welding torch according toclaim 3, wherein the rotor is designed as a motor shaft including arotor winding and a rotor magnet.
 9. A welding torch according to claim6, wherein an insulation plate is fastened to the intermediate piece.10. A welding torch according to claim 6, wherein the drive roller isdirectly fastened to a motor shaft.
 11. A welding torch according toclaim 8, wherein the motor shaft is connected with a gear and the driveroller is coupled to said gear.
 12. A welding torch according to claim7, wherein a gear is provided instead of, or in addition to, theintermediate piece, and the gear is fastened to the torch housing or tothe intermediate piece or to an insulation plate.
 13. A welding torchaccording to claim 1, wherein the torch housing is designed as a coolingbody for the drive motor.
 14. A welding torch according to claim 1,wherein, in a region of the drive motor, cooling channels and/or coolingducts are arranged in the torch housing.
 15. A welding torch accordingto claim 1, wherein the torch housing comprises cooling ribs on itsouter side.
 16. A welding torch according to claim 1, wherein the torchhousing is designed as a gun welding torch for a manual welding torchincluding a grip, and the drive motor is installed in the torch housingin a region of said grip.
 17. A welding torch according to claim 1,wherein a hollowly designed motor shaft is arranged axially to thewelding wire, and the welding wire extends through the hollowly designedmotor shaft.
 18. A welding torch according to claim 1, wherein a controlelectronics for controlling the drive motor is arranged in the torchhousing.
 19. A welding torch according to claim 1, wherein a controlelectronics for the drive motor is arranged externally.
 20. A weldingtorch according to claim 1, wherein at least one switching element isintegrated in the torch housing to control the welding process.
 21. Awelding torch according to claim 1, wherein the torch housing or a partof the torch housing is made of a thermally well conductive materialand/or plastic material.
 22. A welding torch according to claim 1,wherein a mounting plate is arranged in the torch housing.
 23. A weldingtorch according to claim 1, wherein the drive motor is configured as asynchro motor.
 24. A welding torch according to claim 1, wherein thedrive motor is configured as a direct-current motor.
 25. A welding torchaccording to claim 1, wherein the drive motor is designed as a stepmotor.
 26. A welding torch according to claim 8, wherein an insulationis arranged between the drive roller and the base body.
 27. A weldingtorch according to claim 26, wherein said insulation is designed as aninsulation layer formed between the drive roller and the motor shaftand/or the motor shaft and a rotor pack and/or the motor shaft and thebearings and/or the rotor pack and a stator and/or the stator and thetorch housing.
 28. A welding torch according to claim 21, wherein thedrive roller and/or a motor shaft is made of an electricallynon-conductive material.
 29. A welding torch according to claim 1,wherein the torch housing or a part of it is designed as a live part totransmit the welding current.
 30. A welding torch according to claim 1,wherein an insulation layer is applied over at least a part of the torchhousing.
 31. A welding torch according to claim 1, wherein an insulationis provided between a torch retainer and the torch housing, or the torchretainer is made of an electrically non-conductive material.
 32. Awelding torch according to claim 1, wherein the drive motor isexpandable by additional modules to adjust an output and responsebehavior of the drive motor.
 33. A welding torch according to claim 1,wherein an encoder is connected with the rotor or the drive roller. 34.A welding torch according to claim 1, wherein the drive motor comprisesa memory module for recognizing drive motor characteristics.
 35. Awelding torch according to claim 1, wherein several drive motors arearranged in the torch housing.
 36. A welding torch according to claim 6,wherein a tension lever for the pressure roller and a bearing of thepressure roller are arranged on the intermediate part.
 37. A weldingtorch according to claim 1, wherein the torch housing is divided along arotor axis.